Project Masihambisane: a cluster randomised controlled trial with peer mentors to improve outcomes for pregnant mothers living with HIV by Rotheram-Borus, M, Richter, L, Van Rooyen, H, van Heerden, A, Tomlinson, M, Stein, A, Rochat, T, de Kadt, J, Mtungwa, N, Mkhize, L, Ndlovu, L, Ntombela, L, Comulada, W, Desmond, K, Greco, E